(1) Field of the Invention
This invention is concerned with a machine for performing a roughing operation progressively along marginal portions of a shoe bottom.
A progressively operating roughing machine is described in U.S. Pat. No. 4,391,011. The machine there described comprises two shoe supports whereby shoes supported by the shoe supports can be roughed one after the other.
In using this machine, left shoes could be supported by one shoe support and right shoes by the other so that shoes could be operated upon in pairs. In so using the machine, the amount of relative movement between the successively presented shoe supports and the tool supporting means is such that, in the case of each shoe of a pair thus presented, the roughing operation would take place along the inside waist region in the same direction (and thus of course the outside waist region of each shoe of the pair is similarly operated upon) so that, for a pair of shoes thus presented, the roughing operation is a mirror opposite for the left and right shoes, giving a desired uniformity of rough.
However, it is not essential that left shoes be loaded in one shoe support and right shoes in the other, but on the contrary, e.g. all the left shoes of a batch could first be operated upon, using both shoe supports, and thereafter all the right shoes. In such circumstances, it cannot be ensured that a left and a right shoe constituting a pair will be operated upon with the desired degree of uniformity of rough.
More especially, it will be appreciated that, as a roughing tool operates along a marginal portion of a shoe bottom in one direction, it will present to that shoe bottom a leading edge portion by which the roughing operation is essentially carried out, whereas when it operates progressively in an opposite direction, it will present an opposite leading edge portion. The roughing effect of each leading edge portion differs from that of the other in the roughing operation. Thus, in the case of a pair of shoes, in which the inside waist region of one of the shoes has been operated upon by a first leading edge portion and the insole waist region of the other of the pair of shoes has been operated upon by a different leading edge portion, the required uniformity cannot reliably be achieved.
Furthermore, especially in the case of high heeled shoes, there may be a tendency for a roughing tool traversing up an inclined marginal portion of the shoe bottom to "dig" into the material of the shoe bottom, while a tool traversing down such an inclined portion will tend to "bounce".
It is thus the object of the present invention to provide an improved roughing machine in which uniformity of rough can be achieved regardless of the sequence in which shoes are presented.